15315921 has 12 divisors (see below), whose sum is σ = 22372740. Its totient is φ = 10095360.

The previous prime is 15315913. The next prime is 15315931. The reversal of 15315921 is 12951351.

It can be written as a sum of positive squares in 2 ways, for example, as 8346321 + 6969600 = 2889^2 + 2640^2 .

It is not a de Polignac number, because 15315921 - 2³ = 15315913 is a prime.

It is not an unprimeable number, because it can be changed into a prime (15315931) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8760 + ... + 10361.

It is an arithmetic number, because the mean of its divisors is an integer number (1864395).

Almost surely, 2^15315921 is an apocalyptic number.

It is an amenable number.

15315921 is a deficient number, since it is larger than the sum of its proper divisors (7056819).

15315921 is a wasteful number, since it uses less digits than its factorization.

15315921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19216 (or 19213 counting only the distinct ones).

The product of its digits is 1350, while the sum is 27.

The square root of 15315921 is about 3913.5560555587. The cubic root of 15315921 is about 248.3405884502.

The spelling of 15315921 in words is "fifteen million, three hundred fifteen thousand, nine hundred twenty-one".